Subterranean termites construct an extensive foraging gallery beneath the soil surface. A single colony may contain several million termites with foraging territory extending hundreds of feet. Because subterranean termites are cryptic creatures, their presence is not normally known until after some damage, foraging tubes, or live termites (such as swarmers) are found.
There are two general types of termite bait products on the market for controlling termites. One type is the in-ground (IG) system. As described in U.S. Pat. No. 6,397,516, IG systems typically comprise of durable monitoring stations containing monitoring wood pieces that are installed in soil around a house to intercept termites. When termites are found in the stations through a routine monitoring, the infested wood pieces are replaced with baits containing active ingredients (AIs) to kill the termites.
One current IG system utilizes durable baits to bypass the monitoring phase, but baits are still applied in soil to intercept subterranean termites (Su 2007). It is desirable that AIs be non-repellent to induce termite feeding of baits, and be slow-acting so that termites may carry the AIs back and share them with nestmates. Termites are social insects, and members of a colony share interconnected gallery systems extending up to 300 feet. Baits that are consumed by termites from a single station are spread to the entire colony leading to the colony elimination. This IG bait system is used for both preventive and remedial control.
Another type of bait system is intended for remedial control only, and is designed to be placed over active infestation of termites so that termites may come into bait stations to feed on baits. Since the bait system is typically used in the above-ground portions of a structure, it is usually referred to as an “above-ground” (AG) bait system. U.S. Pat. No. 6,370,812 described one such AG bait system comprised of a bait box with one open side mounted on a wall that is infested with termites. Baits are placed in contact with termites in the box before it is closed with a lid. This arrangement allows termites to enter the AG station to consume baits. However, one requirement for successful termite control with an AG system is a completely sealed AG station to prevent air flow, where airflow discourages termites from entering the AG station. Placement of the rigid AG bait box on uneven surfaces without creating a gap can be challenging. Often, where there is a gap between the flat surface of the open side of the AG box, the uneven surface has to be sealed off with additional tapes or other means in order to encourage termite entry into the AG box.
U.S. Pat. Nos. 6,195,934 and 6,370,814 attempted to solve the placement problems by providing unique openings and configurations of AG bait boxes so that they can more precisely intercept termites in their foraging tubes without creating too much gaps. Another solution was to use a flexible enclosure as a bait container so that it may be adhered over surfaces of various contours (Su et al. 1997). Due to the tamper-proof concerns, however, the flexible AG stations with soft enclosures are currently not commercially available.
Another problem with the current AG bait system is that it can be unsightly and intrusive because the AG stations are usually installed in a house visible to residents who dislike to be reminded of the presence of termites, even those inside the AG boxes. Moreover, the bulky AG station may not be installed over the active termite infestation in a tight spot where no room is available to accommodate the AG box.
Fluid formulations containing AIs are available for controlling termite infestations. These formulations, however, do not contain feeding medium. Instead they are intended to be injected into wooden cavities to deposit AIs on the inner surface of the wood cavities to form a bait by using the wood as the feeing medium. When placed in the wooden cavities, the AI-containing fluid formulations dehydrate when adjacent materials, such as wood, absorb the liquid phase of the formulations. This leaves an unpredictable AI concentration on the wood surface, depending on the existing wood moisture and relative humidity. Repellency and feeding deterrence of most AIs are concentration-dependent, and unless they are properly formulated, dehydrated baits generally will not satisfy the necessary non-repellency and slow-acting characteristics needed to control and kill termites.
U.S. Publication No. 2011/0225875, for example, describes a wooden bait system with reservoirs to receive liquid insecticides, such as borates, before the treated bait is placed on or in soil to intercept termites. Because the liquid formulations do not contain feeding medium, and instead the feeding medium is the treated wood, when the liquid in the borate solution is absorbed by the wood, the treated wood surface in the reservoirs may not contain a desired concentration of the borate that is both non-repellent and slow-acting for controlling termites.
Australian Patent No. 1,597,293 (the '293 patent) and a corresponding Great Britain Patent, No. 1,561,901, describe a method which involves mixing termiticide with a food matrix comprising cellulose and a binding agent to form a past-like bait. The '293 method, however, did not address the problem of introducing sufficient quality of bait into termite galleries through small and restricted injection port since only a limited quality of past-like bait may be smeared or pushed into the galleries if the access port is restricted. The method described in the '293 patent relies on the termite ingesting the termiticide along with the matrix, then returning to the colony to introduce the termiticide to other termites through the natural process of trophallaxis (food exchange between termites). Furthermore, the '293 method fails to ensure that the moisture will remain in the food matrix/termiticide combination to ensure proper concentration of termiticide is presented to termites. Over time, dehydration of the '293 mixture affects the concentration of the termiticide, which will also affect the repellency and activity characteristics of the termiticide. Moreover, even a moistened sawdust-agar food matrix will desiccate and degrade within a few days when placed in a dry soil and become unpalatable to termites. Thus, the '293 has no means for ensuring the termiticide will be transmitted to a termite infestation, let alone provide a method for controlling the infestation.
Accordingly, a fluid bait matrix is needed to solve the above-mentioned problems associated with current bait matrices used for controlling termites.